Well, now I might be at least mildly interested in this, after playing a bit of Super Smash Bros. Brawl with my brother and sister. Still not enough to buy it at full price, but enough to consider buying it eventually, though it might be good to get the first two games as well. Though, I have to say, I don't know why they are putting it on the 3DS as well as the Wii U...a game like this really isn't suited for a handheld console at all. I know you can still play single-player mode and online, but...this is the kind of game that really works best with local multiplayer. And for all we know, that could mean that the Wii U version will be scaled back to be more similar to the 3DS one. I do hope, though, that if I do get it, they keep the control customization and let you play with a GamePad, Pro Controller, or Classic Controller (the Wiimote and Nunchuck can just go die)...and let you use the D-pad or left analog stick and map "smash" to something else.
I'm working on a hack! Check it out here